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One-year survival and outcomes of infants born at 22 and 23 weeks of gestation in Sweden 2004–2007, 2014–2016 and 2017–2019
  1. Aijaz Farooqi1,
  2. Stellan Hakansson1,2,
  3. Fredrik Serenius3,
  4. Karin Kallen4,
  5. Lars Björklund5,
  6. Erik Normann3,
  7. Magnus Domellöf6,
  8. Ulrika Ådén7,
  9. Thomas Abrahamsson8,
  10. Anders Elfvin9,10,
  11. Karin Sävman10,
  12. Petra Um Bergström11,
  13. Olof Stephansson12,
  14. David Ley13,
  15. Lena Hellstrom-Westas3,
  16. Mikael Norman14,15
  1. 1 Department of Clinical Sciences, Pediatrics, Umeå University, Umea, Sweden
  2. 2 Pediatrics, Swedish Neonatal Quality Register, Umeå Universitet, Umea, Sweden
  3. 3 Department of Women’s and Children’s Health, Uppsala University, Uppsala, Sweden
  4. 4 Department of Reproductive Epidemiology, Lund University, Lund, Sweden
  5. 5 Departments of Clinical Sciences and Pediatrics, Skåne University Hospital Lund, Lund, Sweden
  6. 6 Department of Clinical Sciences—Pediatrics, Umeå universitet Medicinska fakulteten, Umea, Sweden
  7. 7 Woman and Child Health, Karolinska Institute, Stockholm, Sweden
  8. 8 Department of Biomedical and Clinical Sciences and Department of Pediatrics, Linköping University, Linkoping, Sweden
  9. 9 Department of Pediatrics, Institute of Clinical Sciences, University of Gothenburg Sahlgrenska Academy, Gothenburg, Sweden
  10. 10 Department of Pediatrics, Sahlgrenska University Hospital, Goteborg, Sweden
  11. 11 Clinical Science and Education at Sodersjukhuset, Karolinska Institute, Stockholm, Sweden
  12. 12 Departments of Medicine and Clinical Epidemiology, Karolinska Institutet, Stockholm, Sweden
  13. 13 Department of Clinical Sciences, Pediatrics, Lund University, Lund, Sweden
  14. 14 Neonatal Medicine, Karolinska University Hospital, Karolinska Institute, Stockholm, Sweden
  15. 15 Department of Clinical Sciences, Intervention and Technology, Karolinska Institute, Stockholm, Sweden
  1. Correspondence to Dr Aijaz Farooqi, Department of Clinical Sciences, Pediatrics, Umeå University, Umea 90187, Sweden; aijaz.farooqi{at}


Objective To explore associations between perinatal activity and survival in infants born at 22 and 23 weeks of gestation in Sweden.

Design/Setting Data on all births at 22 and 23 weeks’ gestational age (GA) were prospectively collected in 2004–2007 (T1) or obtained from national registers in 2014–2016 (T2) and 2017–2019 (T3). Infants were assigned perinatal activity scores based on 3 key obstetric and 4 neonatal interventions.

Main outcome One-year survival and survival without major neonatal morbidities (MNM): intraventricular haemorrhage grade 3–4, cystic periventricular leucomalacia, surgical necrotising enterocolitis, retinopathy of prematurity stage 3–5 or severe bronchopulmonary dysplasia. The association of GA-specific perinatal activity score and 1-year survival was also determined.

Results 977 infants (567 live births and 410 stillbirths) were included: 323 born in T1, 347 in T2 and 307 in T3. Among live-born infants, survival at 22 weeks was 5/49 (10%) in T1 and rose significantly to 29/74 (39%) in T2 and 31/80 (39%) in T3. Survival was not significantly different between epochs at 23 weeks (53%, 61% and 67%). Among survivors, the proportions without MNM in T1, T2 and T3 were 20%, 17% and 19% for 22 weeks and 17%, 25% and 25% for 23 weeks’ infants (p>0.05 for all comparisons). Each 5-point increment in GA-specific perinatal activity score increased the odds for survival in first 12 hours of life (adjusted OR (aOR) 1.4; 95% CI 1.3 to 1.6) in addition to 1-year survival (aOR 1.2; 95% CI 1.1 to 1.3), and among live-born infants it was associated with increased survival without MNM (aOR 1.3; 95% CI 1.1 to 1.4).

Conclusion Increased perinatal activity was associated with reduced mortality and increased chances of survival without MNM in infants born at 22 and 23 weeks of GA.

  • neonatology
  • paediatrics

Data availability statement

Data are available on reasonable request.

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Data availability statement

Data are available on reasonable request.

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  • Contributors KK (2004–2007), AF,SH and MN (2014–2016 and 2017–2019) had full access to all data in the study and took responsibility for the integrity of the data. All authors conceived of the study idea. AF, SH and MN drafted the manuscript. AF, KK, FS, MD, MN and LB performed the statistical analyses. All authors were responsible for acquiring, analysing and interpreting data. All authors critically revised the manuscript and approved the final version of the manuscript. AF had full access to the data in the study. AF is guarantor.

  • Funding MN was supported by a grant from a regional agreement on clinical research (ALF) between Region Stockholm and Karolinska Institute (2020-0443) and by the Childhood Foundation of the Swedish Order of Freemasons. The Swedish Neonatal Quality Register was funded by the Swedish Government (Ministry of Health and Social Affairs) and the body of Regional Health Care Providers.

  • Disclaimer The funders had no role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript and decision to submit the manuscript for publication.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.